Traction therapy is a process wherein a patient's spine is placed in tension in order to relieve structural anomalies. Traction apparatus per se is well known for example from Wilhelm U.S. Pat. No. 2,940,442 issued June 14, 1960 and Siltamaki U.S. Pat. No. 3,168,094, issued Feb. 2, 1965. In such a system, it is customary for the patient to wear a head or a chin harness, recline on the treatment table, and then a traction line is attached to the harness, after which a tension pull will be exerted on the harness through the flexible line. Often it is desirable to apply tensile loads which are quite high, sometimes as high as 200 pounds. Some of these loads can sound quite frightening to the patient when he first hears of them, and of course they cannot generally be applied abruptly. Instead they should be applied in a carefully controlled manner and under the most relaxing and reassuring of circumstances.
It is best practice for the device to operate as quietly as possible, in order not to distract the patient, because the rooms in which traction processes are carried out are generally very quiet. Sharp clicks can startle the patient and prevent the desired relaxation. Also it is desirable to be able to increase or decrease the tensile loads in increments to permit the patient to develop a tolerance to the desirable heavier loads, both over a long period of time, and also during the course of a treatment which might last as long as an hour.
It is also a desirable feature that there be safety provisions which will prevent exertion of excessive force, exertion of force in excess of a pre-selected value, or the sudden release of line tension.
It is desirable that, when programming apparatus to develop tension, there be a coincidence between the desired and the attained values. There exist in the prior art some devices which are springily responsive to the force on the flexible line, examples being the said Wilhelm and Siltamaki patents. However, these devices are not adapted for carrying out a variety of programmed sequences.
It is desirable to be able to program the apparatus for a wide range of programs in order to provide the therapist with a broad range of options for treating the patient. In Petulla U.S. Pat. No. 3,786,803, issued Jan. 22, 1974, ratchet means is provided on the device of the said Siltamaki patent in order to increase the tension by some given increment at the end of each cycle. However, this ratchet is a noisy device, and is not functionally adaptable other than to provide a stepwise increase in tension after a previous tension level has been attained. Traction equipment is costly, and it is a very useful objective for one machine to be programmable to a wide variety of sequences and loads, and even to be adaptable to new and different programming as new and different sequences may be conceived in the future.
It is an object of this invention to provide a therapeutic apparatus which is programmable to provide a large number of programmed sequences, and which operates reliably and silently to provide a tension force in the flexible line which closely corresponds to the programmed value.
It is another object of this invention to provide a tension sensing means for such apparatus which is compact, convenient to use, and readily adaptable to use in programmed apparatus.
This invention includes a flexible line attachable to a harness, and drive means to which the line is engaged for pulling it in and paying it out. A motor is operatively engaged to the drive means, and a motor control means is operatively interposed between the motor and a source of energy for driving the motor. The motor control means has a first and a second control condition for respectively causing the motor to pull in or pay out the line, and a third control condition where it does neither. Tension sensing means is responsive to tension exerted on the line and is adapted to provide a signal which is proportional to the value of the tension.
Program means comprises circuitry defining a pre-determined sequence of motor operations to establish a pre-determined sequence of tensions on the line. The program means is operationally coupled to the tension sensing means and to the motor control means to cause the motor control means sequentially to assume appropriate ones of its control conditions so as to attain the pre-determined sequence of tensions in the line.
According to a preferred but optional feature of the invention, the motor control means includes a comparator means for comparing the signal from the tension sensing means to a signal representative of a value selected by a sequence means. The motor control means assumes a respective condition which causes the motor to operate or not to operate to attain the selected value.
According to another preferred but optional feature of the invention, the tension sensing means includes a compression spring responsive to line tension, whose length is proportional to the line tension, and which can be used as a means for generating a signal proportional to the line tension.